let str = 'abcd?';
console.log(str.charCodeAt(4),
	str.codePointAt(4));

for (let c of str) {
	console.log(str);
}

console.log(str.includes('a'),
	str.include(''),
	str.includes(),
	'undefined'.includes(),
	str.includes('a', 3),
	str.includes('a', -5),
	'1234'.includes(2));

console.log(str.startsWith('a'),
	str.startsWith('a', 1),
	str.startsWith('b', 1),
	str.endsWith('?'),
	str.endsWith('d'),
	str.endsWith('d', 4),
	str.endsWith(),
	'undefined'.endsWith(),
	'undefined'.endsWith(undefined));
